The roles of HRCT and clinical parameters in assessing activity of suspected smear negative pulmonary tuberculosis

BACKGROUND: Smear-negative pulmonary tuberculosis (SNPTB) constitutes a major problem in countries with a moderate or high TB prevalence. The value of high-resolution computed tomography (HRCT), chest x-ray and other clinical findings in determining activity of SNPTB were investigated. METHODS: The study population consisted of 85 patients with suspected SNPTB, of whom 52 were confirmed as active pulmonary TB according to either culture positivity for Mycobacteriun tuberculosis or demonstration of caseous granulomatous inflammation. The remaining 33 patients accepted inactive TB sequel. RESULTS: Cough and expectoration were significantly frequent in inactive group whereas chest pain was detected higher in active patients. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of HRCT in detecting disease activity were 88, 88, 92, 83 and 88%, respectively. Centrilobular nodules, other non-calcified nodules, consolidation and cavity were significantly higher on HRCT in active group. Chest x-ray scores that were graded 1 to 3 showed a linear trend for the disease activity. CONCLUSIONS: HRCT has good diagnostic value in detecting activity of SNPTB, and some clinical findings may help in predicting the activity.